1. Field of the Invention
This invention relates generally to intra-channel clarifiers and, more particularly, to devices which limit or control turbulence within intra-channel clarifiers.
2. Prior Art
In oxidation ditch sewage treatment systems, intra-channel clarifiers are often employed. Examples of intra-channel clarifiers may be seen in Harold J. Beard's U.S. Pat. Nos. 4,362,625; 4,383,922 and 4,457,844. Such clarifiers function by utilizing the hydraulic head losses created by a moving stream of sewage as it passes around and/or under a stationary semi-submerged structure. Differential pressures between the interior and the exterior of the clarifier and reduced velocities within the clarifier accelerate settlement of sludge from the wastewater. Sludge is withdrawn from the bottom of the clarifier through a series of sludge removal ports of some type, and the clarified liquid is then removed from the clarifier.
A problem which has developed with some intra-channel clarifiers results from the fluid dynamics of particular clarifier/oxidation ditch configurations. In some situations, turbulence develops within the clarifier, hindering flocculation and settlement of sludge. The turbulence is generally caused by small eddy currents which are carried into the clarifier via entering wastewater. Turbulence may also be caused by reverse flow through sludge removal ports, causing settled sludge to puff up into clarified fluid. It is desirable to encourage early sludge settlement and removal at an early stage in the clarification process, in order to minimize the effects of turbulence.